Waste management technology development and demonstration programs at Brookhaven National Laboratory

Two thermoplastic processes for improved treatment of radioactive, hazardous, and mixed wastes were developed from bench scale through technology demonstration: polyethylene encapsulation and modified sulfur cement encapsulation. The steps required to bring technologies from the research and development stage through full scale implementation are described. Both systems result in durable waste forms that meet current Nuclear Regulatory Commission and Environmental Protection Agency regulatory criteria and provide significant improvements over conventional solidification systems such as hydraulic cement. For example, the polyethylene process can encapsulate up to 70 wt pct. nitrate salt, compared with a maximum of about 20 wt pct. for the best hydraulic cement formulation. Modified sulfur cement waste forms containing as much as 43 wt pct. incinerator fly ash were formulated, whereas the maximum quantity of this waste in hydraulic cement is 16 wt pct

Do You Need a Job to Find a Job?

This paper investigates whether job offers arrive more frequently for those in employment than for those in unemployment. To this end, we take advantage of a unique Australian data set which contains information on both accepted and rejected job offers. Our estimation strategy takes account of the selectivity associated with the initial employment state and we allow for individual heterogeneity in the probability of obtaining jobs. Our results reveal that, across the wage range, individuals are about equally likely to obtain a job offer in employment as in unemployment. This implies that encouraging unemployed (rather than employed) search through the provision of unemployment benefits does not improve the speed of a job match.job-offer arrival rates, reservation wages, wage-offer distribution, directed

Do You Need a Job to Find a Job?

This paper investigates whether job offers arrive more frequently for those in employment than for those in unemployment. To this end, we take advantage of a unique Australian data set which contains information on both accepted and rejected job offers. Our estimation strategy takes account of the selectivity associated with the initial employment state and we allow for individual heterogeneity in the probability of obtaining jobs. Our results reveal that, across the wage range, individuals are about equally likely to obtain a job offer in employment as in unemployment. This implies that encouraging unemployed (rather than employed) search through the provision of unemployment benefits does not improve the speed of a job match.job-offer arrival rates, reservation wages, wage-offer distribution, directed search

Do you need a job to find a job?

This paper investigates whether job offers arrive more frequently for those in employment than for those in unemployment. To this end, we take advantage of a unique Australian data set which contains information on both accepted and rejected job offers. Our estimation strategy takes account of the selectivity associated with the initial employment state and we allow for individual heterogeneity in the probability of obtaining jobs. Our results reveal that, across the wage range, individuals are about equally likely to obtain a job offer in employment as in unemployment. This implies that encouraging unemployed (rather than employed) search through the provision of unemployment benefits does not improve the speed of a job match

Mixtures of tails in clustered automobile collision claims

Knowledge of the tail shape of claim distributions provides important actuarial information. This paper discusses how two techniques commonly used in assessing the most appropriate underlying distribution can be usefully combined. The maximum likelihood approach is theoretically appealing since it is preferable to many other estimators in the sense of best asymptotic normality. Likelihood based tests are, however, not always capable to discriminate among non-nested classes of distributions. Extremal value theory offers an attractive tool to overcome this problem. It shows that a much larger set of distributions is nested in their tails by the so-called tail parameter. This paper shows that both estimation strategies can be usefully combined when the data generating process is characterized by strong clustering in time and size. We find that the extreme value theory is a useful starting point in detecting the appropriate distribution class. Once that has been achieved, the likelihood-based EM-algorithm is proposed to capture the clustering phenomena. Clustering is particularly pervasive in actuarial data. An empirical application to a four-year data set of Dutch automobile collision claims is therefore used to illustrate the approach

Real-Time Monitoring of Low-Level Mixed-Waste Loading during Polyethylene Microencapsulation using Transient Infrared Spectroscopy

In polyethylene microencapsulation, low-level mixed waste (LLMW) is homogenized with molten polyethylene and extruded into containers, resulting in a lighter, lower-volume waste form than cementation and grout methods produce. Additionally, the polyethylene-based waste form solidifies by cooling, with no risk of the waste interfering with cure, as may occur with cementation and grout processes. We have demonstrated real-time monitoring of the polyethylene encapsulation process stream using a noncontact device based on transient infrared spectroscopy (TIRS). TIRS can acquire mid-infrared spectra from solid or viscous liquid process streams, such as the molten, waste-loaded polyethylene stream that exits the microencapsulation extruder. The waste loading in the stream was determined from the TIRS spectra using partial least squares techniques. The monitor has been demonstrated during the polyethylene microencapsulation of nitrate-salt LLMW and its surrogate, molten salt oxidation LLMW and its surrogate, and flyash. The monitor typically achieved a standard error of prediction for the waste loading of about 1% by weight with an analysis time under 1 minute